The St. Lucie Estuary and southern Indian River Lagoon saw a decline in habitat health this week as freshwater inflows more than doubled, lowering salinity levels and nudging overall conditions from a C grade on Sept. 24 to a C- on Oct. 1. The latest report covers the week of Sept. 29, 2025.
Monitoring data showed inflows rising from 1,049 cubic feet per second to 2,341 cfs over the week, while discharges from Lake Okeechobee remained at zero.
The surge in inflows pushed salinity from poor-to-good levels on Sept. 24 down to poor-to-fair by Oct. 1.
Oxygen conditions ranged from poor to good, while water clarity held steady in the fair-to-good range for seagrass. Despite stable clarity, oysters are showing signs of stress under the changing conditions.
The Florida Oceanographic Society’s Weekly Water Quality Report placed the region’s overall habitat-health score at 70 percent for Sept. 25 to Oct. 1, earning a C- grade and a “satisfactory” status.
The Inlet Area posted the highest score at 81 percent (B), with dissolved oxygen of 4.8 milligrams per liter rated fair. Narrow Middle River followed at 77 percent (C) with oxygen at 5.1 mg/L rated good, and the Indian River Lagoon scored 76 percent (C) with oxygen at 5.2 mg/L rated good.
Other zones showed more mixed results. Winding North Fork and Manatee Pocket each scored 71 percent (C). Oxygen was measured at 3.3 mg/L (fair) in the North Fork and 4.8 mg/L (fair) in Manatee Pocket.
North Fork and South Fork both came in at 61 percent (D), each with fair oxygen levels of 4.6 mg/L and 4.3 mg/L.
Winding South Fork scored 66 percent (D), weighed down by poor oxygen at 2.8 mg/L, while Wide Middle River matched the North and South Fork at 61 percent (D) with oxygen at 4.5 mg/L (fair). The Intracoastal Waterway South had no available data.
Citizen science underpins the monitoring effort. Volunteer participants record water temperature, salinity, dissolved oxygen, pH, and water clarity on a weekly basis.
These parameters provide insight into the current health of the estuary and the suitability of the habitat for key indicator species such as seagrass and oysters.
The program currently tracks 47 active monitoring sites across 10 zones in the St. Lucie Estuary and Indian River Lagoon.